Background and Jus&fica&on. Evalua&ng Ples%odon spp. skinks as poten&al reservoir hosts for the Lyme disease bacterium Borrelia burgdorferi 11/5/12

Transcription

1 Evalua&ng Ples%odon spp. skinks as poten&al reservoir hosts for the Lyme disease bacterium Borrelia burgdorferi Teresa Moody, M.S. Candidate Advisor: Dr. Graham Hickling Center for Wildlife Health University of Tennessee Outline Background and Jus&fica&on Research Objec&ves Methods Research Ques&ons Lizard Husbandry Field Components Future Direc&ons Background and Jus&fica&on 1

2 What is Lyme disease? Most common vectorborne disease in US ( Spirochetal bacteria Vector transmioed; by Ixodes spp. &cks through bites Disease agent Vector internaqonal/iv- borrelia/ Z/Ticks/body_Ticks_il3.htm Human Lyme Cases in the United States Distribu&on of Human Disease Distribu&on of Vector Ticks? CDC map adapted by G. Hickling How are Lyme bacteria maintained in nature? Requires a reservoir host In the North: small mammals and birds In the Southeast: lizards Does southern &cks preference for lizards explain why Lyme disease is uncommon in the South? 508_LD_Brochure.pdf 2

3 Lizards and Ticks In the Southeast, lizards are oxen more abundant than rodents (Apperson et al. 1993) Lizards are suitable hosts for Ixodes scapularis 3-88% of skinks infested with &cks (Apperson et al. 1993, Swanson and Norris 2007, Levine et al. 1997) 0-20% rodents infested with &cks (Apperson et al. 1993) Lizards and Bacteria Many lizard species are not thought to be reservoirs for the Lyme disease bacterium Western fence lizard (Lane and Loye, 1989; Lane, 1990; Manweiler et al., 1992; Lane et al., 2006) European sand lizard (Matuschka et al., 1992) However, Borrelia- posi&ve skinks have been found in three eastern U.S. studies (11-36% prevalence; Levin et al. 1996; Swanson and Norris 2007; Clark et al. 2005) The poten&al for Borrelia transmission from skinks to other hosts, including humans, remains unknown Research Objec&ves 3

4 Research Objec&ves Q1. Are some skinks reservoirs for naturally- occurring B. burgdorferi? Q2. Are uninfected skinks capable of becoming reservoirs for B. burgdorferi origina&ng from infected &cks? Q3. If skinks can act as reservoirs of B. burgdorferi, can I. scapularis transmit these strains i) to other rep&les and ii) to rodents? Methods Methods: Go catch skinks!, they said! 4

5 Collec&on sites hwp://wildlifehealth.tennessee.edu/lyme_gradient/sites.htm Sample sizes 10 Broadheads 14 Five- lined 6 Southeastern Five- lined = 3 groups of 10 lizards for trials 11 PLLA hatchlings 2 PLIN hatchlings PLFA = 14 PLIN = 6 PLLA = 33 Lizard housing 5

6 Methods for Q1: Are some skinks reservoirs for naturally- occurring B. burgdorferi? Test naturally aoached &cks Apply???? Xenodiagnos&c? Larvae and test?? Prevalence? Xenodiagnosis high sensi&vity test Methods for Q2: Are uninfected skinks capable of becoming reservoirs for B. burgdorferi origina&ng from infected &cks? Apply infected nymphs to lizards Collect and test Apply xenodiagnos&c larvae to lizards Collect and test Test subset for natural infec&on Clear infec&on? Test subset for infec&on Acquire infec&on? Infec&on? 6

7 Methods for Q3 : Persistence and Transmission Wild skinks Collect naturally aoached larvae and nymphs Borrelia nega&ve skink and control mouse Apply xeno larvae No Test xeno &cks and natural &cks Borrelia posi&ve? Yes Prevalence? Apply Bb infected nymphs and 1 week uninfected larvae Re- apply xeno larvae 3 weeks 9 weeks Infec&on? Persistence? Natural Borrelia posi&ve skinks Re- apply xeno larvae 3 weeks 9 weeks Persistence? Allow infected larvae to molt. Apply as nymphs to naiive skinks and mice. Test with xeno larvae. Transmission? Test dropped &cks How to put &cks on lizards: Bag + &cks + lizard = Tick collec&on and Borrelia tes&ng Lizards held over water for up to 2 weeks to collect engorged &cks Preserve &cks in 70% EtOH Extract total DNA Run PCR tests for Borrelia Sequencing to determine Borrelia species 7

8 Analysis Es&mate prevalence of Borrelia in natural and experimental lizard samples Prevalence = Number of infected lizards Total number of lizards in trial Es&mate persistence of infec&on in lizards Incorporate these parameter es&mates into the Lyme Gradient Project s simula&on models Future Direc&ons Future Direc&ons Con&nue with flow chart through three total groups, to have ample sample size for the lab- infec&on trial Sample addi&onal lizards from coastal NC, SC and FL in spring/summer 2013, to improve the natural infec&on prevalence es&mate 8

9 Acknowledgements Dr. Graham Hickling Dr. Deb Miller Dr. Robert Trigiano Jill Wilson Bull Dr. Jean Tsao Dr. Rick Gerhold Mabre Brand Cody Parmer Gena Pang Dr. Brian Stevenson Lauren Maestas Kostas Damiris Cara Brown Patrick Monari Nathan Wilhite Grant Self Will Peay Lacy Rucker Caroline Grunenwald Family and Friends The Lyme Gradient Project Literature Cited Apperson, C. S., et al RelaQve uqlizaqon of repqles and rodents as hosts by immature Ixodes scapularis (Acari: Ixodidae) in the coastal plain of North Carolina, USA. Experimental & Applied Acarology, (17) Clark, K., et al Molecular idenqficaqon and analysis of Borrelia burgdorferi sensu lato in lizards in the southeastern United States. Applied and Environmental Microbiology, 71(5): Lane, R. S SuscepQbility of the western fence lizard (Sceloporus occidentalis) to the Lyme borreliosis spirochete (Borrelia burgdorferi). American Journal of Tropical Medicine and Hygiene, 42 (1): Lane, R. S., and J. E. Loye Lyme disease in California: InterrelaQonship of Ixodes pacificus (Acari: Ixodidae), the Western Fence Lizard (Sceloporus occidentalis), and Borrelia burgdorferi. Entomological Society of America, 26(4): Lane, R. S., et al Refractoriness of the Western Fence Lizard (Secloporus occidentalis) to the Lyme disease group spirochete Borrelia bisse8i. Parasitology, 92(4): Levin, M., et al Reservoir competence of the southeastern five- lined skink (Eumeces inexpectatus) and the green anole (Anolis carolinensis) for Borrelia burgdorferi. The American Journal of Tropical Medicine and Hygiene, 54(1): Levine, J. F., et al Lizards as Hosts for Immature Ixodes scapularis (Acari: Ixodidae) in North Carolina. Medical Entomology, 34(6): Manweiler et al The western fence lizard Sceloporus occidentalis: evidence of field exposure to Borrelia burgdorferi in relaqon to infestaqon by Ixodes pacificus (Acari:Ixodidae). American Journal of Tropical Medicine and Hygiene, 47 (3): Matuschka, F. R., et al Capacity of European animals as reservoir hosts for the Lyme disease spirochete. Journal of InfecQous Diseases, 165 (3): Swanson, K. I. and D.E. Norris DetecQon of Borrelia burgdorferi DNA in lizards from Southern Maryland. Vector- Borne and ZoonoQc Diseases, 7(1): Experiment Ques&ons? QuesQons? 9